private GifHeaderInfo readHeader()

in src/main/java/org/apache/commons/imaging/formats/gif/GifImageParser.java [746:824]
69 lines of code
12 McCabe index (conditional complexity)

    private GifHeaderInfo readHeader(final InputStream is,
            final FormatCompliance formatCompliance) throws ImagingException,
            IOException {
        final byte identifier1 = readByte("identifier1", is, "Not a Valid GIF File");
        final byte identifier2 = readByte("identifier2", is, "Not a Valid GIF File");
        final byte identifier3 = readByte("identifier3", is, "Not a Valid GIF File");

        final byte version1 = readByte("version1", is, "Not a Valid GIF File");
        final byte version2 = readByte("version2", is, "Not a Valid GIF File");
        final byte version3 = readByte("version3", is, "Not a Valid GIF File");

        if (formatCompliance != null) {
            formatCompliance.compareBytes("Signature", GIF_HEADER_SIGNATURE,
                    new byte[] { identifier1, identifier2, identifier3 });
            formatCompliance.compare("version", 56, version1);
            formatCompliance.compare("version", new int[] { 55, 57, }, version2);
            formatCompliance.compare("version", 97, version3);
        }

        if (LOGGER.isLoggable(Level.FINEST)) {
            logCharQuad("identifier: ", ((identifier1 << 16)
                    | (identifier2 << 8) | (identifier3 << 0)));
            logCharQuad("version: ",
                    ((version1 << 16) | (version2 << 8) | (version3 << 0)));
        }

        final int logicalScreenWidth = read2Bytes("Logical Screen Width", is, "Not a Valid GIF File", getByteOrder());
        final int logicalScreenHeight = read2Bytes("Logical Screen Height", is, "Not a Valid GIF File", getByteOrder());

        if (formatCompliance != null) {
            formatCompliance.checkBounds("Width", 1, Integer.MAX_VALUE,
                    logicalScreenWidth);
            formatCompliance.checkBounds("Height", 1, Integer.MAX_VALUE,
                    logicalScreenHeight);
        }

        final byte packedFields = readByte("Packed Fields", is,
                "Not a Valid GIF File");
        final byte backgroundColorIndex = readByte("Background Color Index", is,
                "Not a Valid GIF File");
        final byte pixelAspectRatio = readByte("Pixel Aspect Ratio", is,
                "Not a Valid GIF File");

        if (LOGGER.isLoggable(Level.FINEST)) {
            logByteBits("PackedFields bits", packedFields);
        }

        final boolean globalColorTableFlag = ((packedFields & 128) > 0);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("GlobalColorTableFlag: " + globalColorTableFlag);
        }
        final byte colorResolution = (byte) ((packedFields >> 4) & 7);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("ColorResolution: " + colorResolution);
        }
        final boolean sortFlag = ((packedFields & 8) > 0);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("SortFlag: " + sortFlag);
        }
        final byte sizeofGlobalColorTable = (byte) (packedFields & 7);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("SizeofGlobalColorTable: "
                    + sizeofGlobalColorTable);
        }

        if (formatCompliance != null) {
            if (globalColorTableFlag && backgroundColorIndex != -1) {
                formatCompliance.checkBounds("Background Color Index", 0,
                        convertColorTableSize(sizeofGlobalColorTable),
                        backgroundColorIndex);
            }
        }

        return new GifHeaderInfo(identifier1, identifier2, identifier3,
                version1, version2, version3, logicalScreenWidth,
                logicalScreenHeight, packedFields, backgroundColorIndex,
                pixelAspectRatio, globalColorTableFlag, colorResolution,
                sortFlag, sizeofGlobalColorTable);
    }